Programma della conferenza

Biotic interactions are crucial processes that shape ecosystem structure and functioning. Climate change significantly alters the nature and strength of species interactions by influencing species responses, tolerance thresholds, and distributions, thereby defining "winners" and "losers" under changing environmental conditions. Here, we outline the trend of a recently intensified interaction between an endemic Mediterranean structuring species (the coral Astroides calycularis) and a range-expanding predator (the fireworm Hermodice carunculata) under warming conditions. The thermal performance curves of both species were experimentally defined, identifying their thermal optimum temperatures and tolerance thresholds. Additionally, the feeding response of the polychaete on the coral was studied and modeled. Trait-based maps showed that current warm temperatures and forecasted climatic conditions pose a significant risk to the shallow coral, with environmental temperatures exceeding its upper thermal threshold; while benefiting the fireworm by enhancing its spread and maximizing its metabolic and feeding performance at high temperatures. The interacting species’ responses to temperature and the feeding performance of the predator were integrated to create a vulnerability index to predict the risk to which the habitat-forming species may be exposed. Investigated interacting stressors may synergistically jeopardize the integrity of this biodiversity hotspot habitat, reducing its complexity and leading to biodiversity loss.

On October 7^th 2018, approximately 15 miles north of Capo Corso (Corsica), a major oil spill occurred as a result of the collision of a Tunisian ferry with a stationary cargo ship and six hundred cubic meters of oil were dispersed into the sea. At that time, part of the Puffinus yelkouan population had already returned to breeding areas comprising a large fraction of the global population. We evaluated the potential toxicological effects of oil spill contamination in yelkouan shearwater individuals from Italian breeding areas after the oil spill accident. Different nesting areas were sampled in the breeding season: Montecristo was close to the oil spill area, Tavolara and Molara islands host over the 50% of the global population and Capo Carbonara MPA (Villasimius, southern Sardinia) was chosen as a control area, being far from the oil spill area. Polycyclic aromatic hydrocarbons (PAHs) accumulation, genotoxic and immune system markers were assessed in blood samples collected from 33 breeding adults. In addition, porphyrin levels were measured in feacal samples. Similar and quite high levels of low molecular weight hydrocarbons (naphthalene, acenaphthene, fluorene, and phenanthrene) were found in the three areas. We didn’t find immune system alterations, while individuals from Tavolara island showed the highest nuclear abnormalities values, both Tavolara and Villasimius specimens showed statistically significant higher ENA values with respect to Montecristo. These results could indicate that the presence of genotoxic effects is not linked to the collision but caused by other sources of contamination. Furthermore, the highest porphyrin levels were found in specimens from Villasimius area. This study underlines the importance of ecotoxicological studies on endangered seabirds to be able to plan management measures for the conservation of the species.

Marine Protected Areas (MPAs) are crucial tool for conserving biodiversity and ensuring the sustainable use of marine resources. It is well known that MPAs host most of diving destinations due to their rich biodiversity and an increasing number of studies show that diving activities can have damaging effects on marine life, especially on sessile benthic organisms.

The present study aimed to evaluate the pressure of recreational diving activities within the MPA "Secche di Tor Paterno" through a multi-faceted approach. The first component of the study focused on analyzing the abundance and behaviour of the divers. This step allowed for the identification of the factors that most influenced the frequency of disturbance, i.e. diver contacts with the benthic organisms in the MPA. Additionally, the data collected during dives enabled the identification of seabed points most subject to physical disturbance through small-scale spatial analysis. Finally, the activities allowed for a detailed analysis of the potential impacts of scuba diving tourism on the composition and structure of the benthic communities in the MPA, using bioindicators recognized as sensitive to such disturbances.

Results indicated diving experience and use of camera as the most significant factors that influenced the impact on the benthos. Indeed, hotspots frequently disturbed by diving activities coincided with areas attractive to underwater photographers. Despite various contacts with the benthos, no significant changes in bioindicator species diversity were observed due to diving activities. Instead, depth appeared to explain variations in benthic community diversity among dive sites.

This study suggests that scuba diving activities in the MPA “Secche di Tor Paterno” do not significantly alter the benthic community structure, highlighting the sustainability of the diving tourism in the area. Furthrmore, it provides further indication to increase the effectiveness of the MPA management.

The Mediterranean fan mussel Pinna nobilis (L. 1758) has been experiencing since 2016 significant Mass Mortality Events (MMEs), associated with the protozoan Haplosporidium pinnae, which has caused a drastic decline of the species. Between 2019 and 2020 the epidemic reached the northern Adriatic and, subsequently, the Venice Lagoon, where Pinna nobilis was characterized by wide distribution and high densities. Despite the observed MMEs, the Venice Lagoon, one of the largest Mediterranean coastal transitional ecosystems (CTEs, still hosts a large residual population. Comparable situations of higher survival rate are also known for other CTEs, which seems to act as refugia for the species. The distribution and structure of Pinna nobilis remnant populations in the Venice Lagoon and surrounding waters have been investigated since 2021 through multiple approaches across different scales. A site close to Ottagono Alberoni, near Malamocco inlet, has been monitored monthly from October 2020. Video transects were collected in 2021 across the central Lagoon. During 2023, larval collectors were placed at 5 sites along the Veneto coastline in the framework of Life PINNARCA and Interreg IT-SI TRECap projects. In 2024, quantitative surveys over 50 sampling stations have been performed in collaboration with Regione Veneto in the context of Interreg IT-SI POSEIDONE. Overall, the investigations allowed assessing the status of the species, epidemic and population trends as well as spatial patterns. The Venice Lagoon still possibly hosts one of the largest extant population of the species, acting likely as a source of propagules for surrounding marine waters. Both Pinna nobilis distribution and mortality rates appear related to main environmental gradients, such as water exchange and salinity, providing insights into the underlying epidemic dynamics and ecological processes. Present results and main research perspectives will be discussed also in the context of management policies and conservation strategies for the species.